In general, the term “infusion” is to be understood in accordance with the invention as any administering of a for example liquid or solid substance and/or an infusing medium such as for example medicines, cells, genes, enzymes, proteins, antibodies, hormones, viruses or the like, said substance being introduced directly into a body and/or into body tissues, in order for example to surmount the blood-brain barrier. The substance can be delivered within a relatively short period of time, for example through an injection, or over a longer period of time, for example at a continuous and possibly variable rate of delivery of the substance.
Pharmaceutical substances have previously been administered by injecting a substance through the skin, directly into the vascular system, muscle tissue or subcutaneous tissue, or by positioning a catheter such that a substance could be introduced from without directly into body tissues. This depended crucially on the experience of the person who for example positioned the syringe so as to be able to position the substance to be administered as precisely as possible in the desired area of tissue. Due to inaccuracies and lack of knowledge of the substance-specific and patient-specific spreading mechanisms and distribution mechanisms in the corresponding tissue, as well as due to patient-specific variations in the arrangement of the tissue, for example in the case of a diseased tissue, it has been necessary to set a dosage required to treat a particular target tissue relatively high, in order to ensure that the substance delivered can reach the target tissue in a sufficient dosage, even when, due to inaccuracies, the location of injection of the substance does not lie directly in the target tissue. However, such substances, for example for treating tumors, are often toxic and thus unnecessarily debilitate surrounding tissue. If for example a tumor is to be treated using chemotherapy, toxic substances are used which can also damage healthy tissue.
On the other hand, it must be ensured, when performing an infusion, that the infusion locations and infusion parameters enable the infusion target area to be completely treated.
Various methods and devices have already been proposed, for enabling a substance to be introduced into a particular area of tissue in the first place, or for developing this to be more efficient, for example for treating tumors, Parkinson's disease or other illnesses.
It is known from US RE 37,410 E to inject a substance to be administered into a biodegradable material and to arrange the latter within or closely adjacent to a tumor to be treated, in order for example to surmount the blood-brain barrier in the case of a brain tumor. Once the bio-degradable material has degraded, the substance contained in it is released. This method, however, is relatively imprecise with respect to an individual, patient-specific dosage and also cannot be used for a protracted, specific treatment in which the treatment parameters may be altered.
A method for performing micro-infusions is known from U.S. Pat. No. 5,720,720, in which the tip of an infusion catheter is arranged inside a tissue structure. An active agent is delivered through the catheter, wherein a pressure gradient at the tip of the catheter is kept constant during infusion. This is to ensure a better distribution of the active agent, which would not be achievable by fusion alone.
U.S. Pat. No. 6,026,316 describes a method for delivering medicines, using data obtained from magnetic resonance or nuclear spin resonance (MR) to determine the position of the delivery device and to monitor the spatial distribution of the delivered medicine.